Perhaps you should try some spelling variations:
"endoloop-assisted endoscopic resection" » "endoloop-assessed endoscopic resection" (Expand Search), "endoloop-assisted endoscopic reduction" (Expand Search), "endoloop-assisted endoscopic detection" (Expand Search)
"endoloop-assisted endoscopic selection" » "endoloop-assessed endoscopic selection" (Expand Search), "endoloop-assisted endoscopic detection" (Expand Search)

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• Performing a fuzzy search may retrieve terms with similar spellings: (("endoloop-assisted endoscopic resection") OR ("endoloop-assisted endoscopic selection"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"endoloop-assisted endoscopic resection\") OR (\"endoloop-assisted endoscopic selection\"))".
• Removing quotes may allow a broader search: (( endoloop-assisted endoscopic resection ) OR ( endoloop-assisted endoscopic selection )).
• Adding a wildcard symbol may retrieve word variants: (("endoloop-assisted endoscopic resection") OR ("endoloop-assisted endoscopic selection"))*.